Polyarylenes such as poly(p-phenylene) have excellent resistance to thermal oxidative and radiative degradation, and find utility as lubricants, insulators, pigments, ablative materials, oxidation inhibitors, stabilizers against heat and light, binders in heat shields, and the like.
U.S. Pat. No. 3,359,340 describes a process for producing polyphenylene which involves subjecting benzene vapor containing 0.1-5 percent benzoic acid to pyrolytic conditions.
U.S. Pat. No. 3,386,899 discloses the polymerization of benzene and polycyclic aromatic hydrocarbons by anodic oxidation in liquid hydrogen fluoride.
U.S. Pat. No. 3,480,568 discloses the conversion of benzene to poly(p-phenylene) with oxygen in the presence of CuCl.sub.2 /Al.sub.2 O.sub.3 catalyst.
U.S. Pat. No. 3,565,832 discloses the conversion of aromatic hydrocarbons to polymers by reaction with oxygen in the presence of a Lewis Acid catalyst such as BF.sub.3 or FeCl.sub.3.
U.S. Pat. No. 3,798,281 describes a rapid process for producing polyarylenes which involves contacting an aromatic hydrocarbon with an Al.sub.2 O.sub.3 /SiO.sub.2 catalyst in the presence of hydrogen at a temperature of at least about 425.degree. C.
U.S. Pat. No. 3,829,518 describes a dehydrogenative coupling process for the polymerization of partially hydrogenated aromatic hydrocarbons which involves treating a partially hydrogenated aromatic hydrocarbon with a catalyst such as MoO.sub.3 at elevated temperature and pressure in the presence of hydrogen.
U.S. Pat. No. 4,022,717 discloses a process for the oxidative coupling of arenes to polymers, which involves reacting at least one arene other than benzene in liquid hydrogen fluoride with oxygen in the presence of a soluble molybdenum catalyst at a temperature of 0.degree.-120.degree. C.
The prior art methods tend to be limited by one or more disadvantages. These include high consumption of electric power, consumption of large quantities of oxidants, production of polymer products containing toxic impurities, the use of a precious metal catalyst which requires recovery, low conversion to high molecular weight polymers, and the like.
Accordingly, it is an object of this invention to provide an improved process for the production of poly(p-phenylene).
It is another object of this invention to provide a process for producing poly(p-phenylene) with a molecular weight range suitable for conversion to carbon fibers.
Other objects and advantages of the present invention shall become apparent from the accompanying description and example.
Other prior art of interest with respect to the present invention relates to chemical reaction systems which utilize high frequency sonic energy to activate molecular reactions.
U.S. Pat. No. 3,630,866 describes a process for activating intra-chemical reactions which involves subjecting a fluid chemical reactant to ultrasonic energy in the frequency range of 1.times.10.sup.10 to 1.times.10.sup.15 hertz by passing the reactant within 2 microns of a thin layer piezoelectric transducer emitting the ultrasonic energy.
J. Org. Chem., 47, 751(1982) describes ultra-sound promoted reactions of zinc with .alpha.,.alpha.'-dibromo-o-xylene in the presence of dienophiles to yield cycloaddition products via an o-xylene intermediate.
Other organic sonochemistry publications of interest include J. Amer. Chem. Soc., 102, 7926(1980); Tetrahedron Letters, 22(29), 2757(1981); Tetrahedron Letters, 22(39), 3813(1981); and Tetrahedron Letters, 23(16), 1643 (1982).